A baby girl and a three-year-old boy who were rescued from a house fire had been left at home alone.

The little boy was fighting for his life in hospital today after inhaling smoke. He is on a ventilator and has been sedated, the fire service said.

A police spokesman described the boy's condition at the Royal Manchester Children's Hospital as critical.

The one-year-old girl escaped the blaze in Bolton unhurt. A man and a woman, believed to be the children's parents, were not at home when the fire started in an upstairs bedroom at the terrace house on Longden Street in the Heaton area at 6.45pm yesterday.

The woman is believed to have left home a short time earlier.

She returned as fire crews arrived at the scene and was witnessed screaming and shouting for her children outside.

By that time the baby girl had been rescued by a hero neighbour who saw smoke and flames coming from an upstairs window.

The girl was found lying in a pram in a hallway and was taken out to safety.

Six firefighters then charged into the house and rescued the boy from a bed in a separate bedroom.

The cause of the blaze was today being investigated by police and the fire service.

It is not known where the man and woman had been or how long they had been out for when the blaze began.

It is understood that a specialist police child protection unit is involved in the investigation.

A firefighter suffered minor burns to his arm and hand in the rescue and was taken to the Royal Bolton Hospital.

The fire service revealed today that a smoke alarm inside the house wasn't working.

Ian Bailey, Bolton's fire service commander, said: “It is devastating that two young children are in hospital after a fire at their home like this, when their house was fitted with a smoke alarm – but it wasn’t working.

“Thanks to the brave actions of neighbours and our firefighters, the children were rescued from the blaze, but now we are calling upon the community to help us. “Working smoke alarms are crucial and save lives but historically, in some of the predominantly Asian communities, we have had a poor take up our free home safety checks which often include the fitting of smoke alarms.

“Today we are trying to improve that, by working with the Bolton Council of Mosques and using GMFRS volunteers and community safety advisors we can assist in a number of ways.”